Voltage compensator, control method thereof and power supply system

Abstract

The invention discloses a voltage compensator, a control method thereof and a power supply system, and relates to the technical field of power supply. The voltage compensator comprises N energy taking transformers, N thyristor bridge circuits and N compensation transformers, the energy taking transformers and the thyristor bridge circuits are in one-to-one correspondence with the compensation transformers, and N is a positive integer; primary side windings of the energy taking transformers are adjustably connected with power supply lines of the corresponding loads respectively, and secondary side gear taps of the energy taking transformers are connected with the corresponding thyristor bridge circuits respectively; each thyristor bridge circuit is connected with the primary side of the corresponding compensation transformer; and the secondary side of each compensation transformer is connected with the corresponding power supply line. According to the voltage compensator provided by the embodiment of the invention, the number of thyristors and the number of gear taps of the energy taking transformer can be effectively reduced, and compared with a dynamic voltage restorer in the prior art, the voltage compensator provided by the embodiment of the invention can effectively reduce the cost.

Description

Technical Field

[0001] This application belongs to the technical field of power supply, and specifically relates to a voltage compensator, its control method, and a power supply system. Background Art

[0002] Problems such as large voltage fluctuations and low voltage at the end of the distribution network line are particularly common at the end of rural distribution networks and some urban distribution networks. The access of new energy sources such as wind power and photovoltaics will also cause fluctuations in the power grid. Under the requirements of building a new power system, power quality governance is particularly important.

[0003] Traditional voltage governance means mainly include: 1. Installing a distribution transformer at the end of the line, that is, adding a new transformer; 2. Transforming the branch line, such as increasing the cable cross-section or adding a dedicated line for power supply; 3. Transforming the on-load tap-changing transformer, such as expanding the capacity and appropriately adjusting the tap; 4. Installing a low-voltage automatic compensation capacitor for reactive power compensation; 5. Installing an AC voltage stabilizer. The above traditional voltage governance means have limited adjustment capabilities, large workloads, and problems such as difficulties in negotiating the floor area of new equipment and line corridors, and are not easy to promote.

[0004] Based on this, a dynamic voltage restorer (DVR) is currently mainly used to compensate the line where the load is located. However, the dynamic voltage restorer uses a high-power insulated gate bipolar transistor (IGBT) module. The capacitance and inductance used in the filtering circuit supporting the IGBT have high costs, the control system of the IGBT is complex, and the storage unit cost of the dynamic voltage restorer is also high, resulting in a high cost of the dynamic voltage restorer. Summary of the Invention

[0005] The technical problem to be solved by this application is to provide a voltage compensator, its control method, and a power supply system in view of the above deficiencies existing in the prior art. Using this voltage compensator can effectively reduce the number of thyristors and the number of tap-changers of the energy-taking transformer. Compared with the dynamic voltage restorer in the prior art, the voltage compensator provided by the embodiments of this application can effectively reduce costs.

[0006] In a first aspect, an embodiment of this application provides a voltage compensator, including N energy-taking transformers, N thyristor bridge circuits, and N compensation transformers. The energy-taking transformers and the thyristor bridge circuits are respectively in one-to-one correspondence with the compensation transformers, and N is a positive integer;

[0007] For each energy-taking transformer, its primary side winding is respectively adjustablely connected to the power supply line of its corresponding load, and its secondary side tap is respectively connected to its corresponding thyristor bridge circuit; among them, the number of taps of each energy-taking transformer is n, and n is a positive integer;

[0008] Each thyristor bridge circuit is respectively connected to the primary side of its corresponding compensation transformer;

[0009] For each compensation transformer, its secondary side is respectively connected to its corresponding power supply line;

[0010] Among them, each energy-taking transformer obtains electric energy from the power grid connected to its corresponding power supply line, and when its corresponding thyristor bridge circuit is in the target gear position, converts the electric energy into the target compensation voltage, and then outputs the target compensation voltage to its corresponding power supply line through its corresponding thyristor bridge circuit and its corresponding compensation transformer, so as to compensate the current voltage of the load, and further control the voltage of the load within the preset range; among them, the target compensation voltage is the compensation voltage corresponding to the target gear position, and the target gear position is the compensation gear position corresponding to the current voltage of the load among n*(n - 1)+1 gear positions.

[0011] In some embodiments of the first aspect, each thyristor bridge circuit includes a first thyristor unit to an nth thyristor unit; the first thyristor unit includes a first thyristor group and an (n + 1)th thyristor group, the second thyristor unit includes a second thyristor group and an (n + 2)th thyristor group,..., the nth thyristor unit includes an nth thyristor group and a 2nth thyristor group;

[0012] The primary side winding of each energy-taking transformer includes a first tap to an nth tap; the secondary side winding of each energy-taking transformer includes an (n + 1)th tap to an mth tap; where m is a positive integer greater than n; the first ends and second ends of each first thyristor unit to each nth thyristor unit are respectively connected in series with both ends of the primary side of its corresponding compensation transformer;

[0013] The third end of each ith thyristor unit is connected to its corresponding ith tap, where i is an integer greater than or equal to 1 and less than or equal to n;

[0014] Each mth tap is grounded, and one of the (n + 1)th tap to the (m - 1)th tap is adjustably connected to the power supply line of the load connected to its corresponding energy-taking transformer.

[0015] In some embodiments of the first aspect, n = 4.

[0016] In some embodiments of the first aspect, the voltage compensator further includes:

[0017] At least one protection module, each protection module is connected in parallel with its corresponding thyristor bridge circuit between both ends of the primary side of its corresponding compensation transformer, and is used to prevent the secondary side tap of the energy-taking transformer corresponding to the protection module from being short-circuited during the gear shifting and switching process of its corresponding thyristor bridge circuit.

[0018] In some embodiments of the first aspect, each protection module includes a current-limiting reactor and a thyristor group A connected in series between both ends of the primary side of its corresponding compensation transformer.

[0019] In some embodiments of the first aspect, each compensation transformer includes an isolation transformer.

[0020] Based on the same inventive concept, in a second aspect, an embodiment of the present application further provides a voltage compensator control method, which is applied to the voltage compensator according to any one of the first aspect. The method includes:

[0021] Controlling each energy-taking transformer to obtain electric energy from the power grid connected to its corresponding power supply line;

[0022] Controlling the thyristor bridge circuit corresponding to each energy-taking transformer to be in a target gear, where the target gear is the compensation gear corresponding to the current voltage of the load among n*(n - 1)+1 gears;

[0023] Wherein, when the thyristor bridge circuit corresponding to each energy-taking transformer is in the target gear, the electric energy is converted into a target compensation voltage, and the target compensation voltage is output to the power supply line corresponding to each energy-taking transformer through the thyristor bridge circuit and the compensation transformer respectively corresponding to each energy-taking transformer, so as to compensate the current voltage of the load, and further control the voltage of the load within a preset range; wherein, the target compensation voltage is the compensation voltage corresponding to the target gear.

[0024] In some embodiments of the second aspect, before controlling the thyristor bridge circuit corresponding to each energy-taking transformer to be in the target gear, the method further includes:

[0025] Obtaining the current voltage of the load and the rated voltage of the load respectively corresponding to each energy-taking transformer to obtain N current voltages of the load and N rated voltages of the load;

[0026] Determining the target gear of the thyristor bridge circuit corresponding to each energy-taking transformer according to the N current voltages of the load and the N rated voltages of the load.

[0027] In some embodiments of the second aspect, determining the target gear of the thyristor bridge circuit corresponding to each energy-taking transformer according to the N current voltages of the load and the N rated voltages of the load specifically includes:

[0028] For each energy-taking transformer, the following steps are respectively executed to determine the target gear of the thyristor bridge circuit corresponding to each energy-taking transformer:

[0029] Determining the difference between the rated voltage of the load corresponding to the energy-taking transformer and the current voltage of the load corresponding to the energy-taking transformer as the first voltage difference;

[0030] Taking the ratio of the first voltage difference to the current voltage of the load corresponding to the energy-taking transformer as the first voltage ratio;

[0031] Determining the gear position corresponding to the first voltage ratio as the target gear position.

[0032] In some embodiments of the second aspect, controlling each energy-taking transformer to obtain electric energy from the power grid connected to its corresponding power supply line specifically includes:

[0033] When it is monitored that the current voltage of the load is less than the preset voltage and the arm currents on each thyristor bridge circuit are all completely zero-crossing, controlling each energy-taking transformer to obtain electric energy from the power grid connected to its corresponding power supply line.

[0034] In some embodiments of the second aspect, each thyristor bridge circuit includes a first thyristor unit to an nth thyristor unit; the first thyristor unit includes a first thyristor group and an (n + 1)th thyristor group, the second thyristor unit includes a second thyristor group and an (n + 2)th thyristor group,..., the nth thyristor unit includes an nth thyristor group and a 2nth thyristor group;

[0035] The primary side windings of each energy-taking transformer include a first tap to an nth tap; the secondary side windings of each energy-taking transformer include an (n + 1)th tap to an mth tap; where m is a positive integer greater than n; the first ends and second ends of each first thyristor unit to each nth thyristor unit are respectively connected in series with both ends of the primary side of its corresponding compensation transformer;

[0036] Each ith thyristor unit is connected to its corresponding ith tap, where i is an integer greater than or equal to 1 and less than or equal to n;

[0037] Each mth tap is grounded, and one of the taps from the (n + 1)th tap to the (m - 1)th tap of each energy-taking transformer is adjustably connected to the power supply line of the load connected to its corresponding energy-taking transformer;

[0038] The voltage compensator further includes N protection modules, and each protection module is connected in parallel with its corresponding thyristor bridge circuit between both ends of the primary side of its corresponding compensation transformer, and is used to prevent the secondary side gear position taps of the energy-taking transformer corresponding to the protection module from being short-circuited during the gear shifting and switching process of its corresponding thyristor bridge circuit;

[0039] In the case of the target gear position corresponding to each energy-taking transformer, the protection modules corresponding to each energy-taking transformer are turned on, and the first thyristor group to the nth thyristor group are all turned off, or, all the protection modules are turned off, and one of the first thyristor group to the nth thyristor group corresponding to each energy-taking transformer is turned on, and the rest are all turned off, and one of the (n + 1)th thyristor group to the 2nth thyristor group corresponding to each energy-taking transformer is turned on, and the rest are all turned off.

[0040] In some embodiments of the second aspect, n = 4;

[0041] When the target gear is the zero gear, the protection modules corresponding to the energy-taking transformers are turned on, and the first thyristor groups to the eighth thyristor groups respectively corresponding to the energy-taking transformers are all turned off.

[0042] When the target gear is the first gear, the third thyristor group and the eighth thyristor group respectively corresponding to the energy-taking transformers are turned on, and the remaining thyristor groups and the protection modules are all turned off.

[0043] When the target gear is the second gear, the first thyristor group and the sixth thyristor group respectively corresponding to the energy-taking transformers are turned on, and the remaining thyristor groups and the protection modules are all turned off.

[0044] When the target gear is the third gear, the second thyristor group and the seventh thyristor group respectively corresponding to the energy-taking transformers are turned on, and the remaining thyristor groups and the protection modules are all turned off.

[0045] When the target gear is the fourth gear, the second thyristor group and the eighth thyristor group respectively corresponding to the energy-taking transformers are turned on, and the remaining thyristor groups and the protection modules are all turned off.

[0046] When the target gear is the fifth gear, the first thyristor group and the seventh thyristor group respectively corresponding to the energy-taking transformers are turned on, and the remaining thyristor groups and the protection modules are all turned off.

[0047] When the target gear is the sixth gear, the first thyristor group and the eighth thyristor group respectively corresponding to the energy-taking transformers are turned on, and the remaining thyristor groups and the protection modules are all turned off.

[0048] When the target gear is the seventh gear, the fourth thyristor group and the seventh thyristor group respectively corresponding to the energy-taking transformers are turned on, and the remaining thyristor groups and the protection modules are all turned off.

[0049] When the target gear is the eighth gear, the second thyristor group and the fifth thyristor group respectively corresponding to the energy-taking transformers are turned on, and the remaining thyristor groups and the protection modules are all turned off.

[0050] When the target gear is the ninth gear, the third thyristor group and the sixth thyristor group respectively corresponding to the energy-taking transformers are turned on, and the remaining thyristor groups and the protection modules are all turned off.

[0051] When the target gear is the tenth gear, the fourth thyristor group and the sixth thyristor group respectively corresponding to the energy-taking transformers are turned on, and the remaining thyristor groups and the protection modules are all turned off.

[0052] When the target gear is the eleventh gear, the third thyristor group corresponding to each energy extraction transformer conducts, and the fifth thyristor group conducts, and the rest of the thyristor groups and each protection module are cut off;

[0053] When the target gear is the twelfth gear, the fourth thyristor group corresponding to each energy extraction transformer conducts, and the fifth thyristor group conducts, and the rest of the thyristor groups and each protection module are cut off.

[0054] Based on the same inventive concept, in a third aspect, an embodiment of the present application further provides a power supply system, including:

[0055] A load;

[0056] A power supply line, connected to the load, for supplying power to the load;

[0057] A voltage compensator as described in any one of the first aspect, connected to the power supply line, for compensating the current voltage of the load to control the voltage of the load within a preset range.

[0058] Since in a topological structure with the same number of compensation gears, the thyristor bridge circuit can effectively reduce the number of thyristor groups and the number of transformer taps. Therefore, according to the voltage compensator, its control method, and the power supply system provided by the embodiments of the present application, by using a dynamic voltage restorer, a thyristor bridge circuit, and a compensation transformer to construct a voltage compensator, while ensuring that n*(n - 1)+1 gears are provided to compensate the current voltage of the load, and further controlling the voltage of the load within a preset range, so that the voltage of the load remains stable and the safety of the load is ensured, at the same time, the number of thyristors and the number of energy extraction transformer tap positions can be effectively reduced. Compared with the dynamic voltage restorer in the prior art, the voltage compensator provided by the embodiments of the present application can effectively reduce costs. Description of the Drawings

[0059] Figure 1 Shows a schematic structural diagram of a power supply system provided by an embodiment of the present application;

[0060] Figure 2 Shows another schematic structural diagram of a power supply system provided by an embodiment of the present application;

[0061] Figure 3 Shows a simulation diagram of the trigger signal of the first thyristor S1 in the voltage compensator provided by an embodiment of the present application;

[0062] Figure 4 Shows a simulation diagram of the trigger signal of the fourth thyristor S4 in the voltage compensator provided by an embodiment of the present application;

[0063] Figure 5 Shows a simulation diagram of the trigger signal of the eighth thyristor S8 in the voltage compensator provided by an embodiment of the present application;

[0064] Figure 6 The simulation diagram showing the load voltage compensated by the voltage compensator provided in the embodiment of the present application.

[0065] Description of reference numerals:

[0066] 10. Protection module; 20. Thyristor bridge circuit; 21. First thyristor bridge circuit; 22. Second thyristor bridge circuit; 23. Third thyristor bridge circuit; 30. Energy-taking transformer; T 1a , Phase-A energy-taking transformer; T 1b , Phase-B energy-taking transformer; T 1c , Phase-C energy-taking transformer; 40. Compensation transformer; T 2a , Phase-A compensation transformer; T 2b , Phase-B compensation transformer; T 2c , Phase-C compensation transformer; 50. Load; L, Current-limiting reactor; S0. Group of thyristors Jia; S1. First group of thyristors; S2. Second group of thyristors; S3. Third group of thyristors; S4. Fourth group of thyristors;

[0067] S5. Fifth group of thyristors; S6. Sixth group of thyristors; S7. Seventh group of thyristors; S8. Eighth group of thyristors. Detailed implementation manners

[0068] To enable those skilled in the art to better understand the technical solutions of the present application, the present application will be further described in detail below with reference to the drawings and embodiments.

[0069] The features and exemplary embodiments of various aspects of the present application will be described in detail below. To make the objectives, technical solutions and advantages of the present application clearer and more understandable, the present application will be further described in detail below with reference to the drawings and specific embodiments. It should be understood that the specific embodiments described herein are only configured to explain the present application and are not configured to limit the present application. For those skilled in the art, the present application can be implemented without some of these specific details. The following description of the embodiments is only to provide a better understanding of the present application by showing examples of the present application.

[0070] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising..." does not exclude the existence of additional identical elements in the process, method, article or device comprising the said element.

[0071] It should be understood that the term "and / or" used in this article is merely an associative relationship describing associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this article generally represents an "or" relationship between the associated objects before and after.

[0072] Embodiment 1

[0073] The voltage compensator provided by the embodiment of the present application is applicable to the process of a power supply system supplying power to a load.

[0074] As Figure 1 and Figure 2 shown, taking N = 3 and N = 1 as examples, the voltage compensator provided by the embodiment of the present application includes N energy-taking transformers 30, N thyristor bridge circuits 20 and N compensation transformers 40. The energy-taking transformers 30 and the thyristor bridge circuits 20 are respectively in one-to-one correspondence with the compensation transformers 40, and N is a positive integer.

[0075] As an example, as Figure 1 shown, for the convenience of description, in the embodiment of the present application, the 3 energy-taking transformers 30 are respectively denoted as the A-phase energy-taking transformer T 1a , the B-phase energy-taking transformer T 1b and the C-phase energy-taking transformer T 1c . The 3 thyristor bridge circuits 20 are respectively denoted as the first thyristor bridge circuit 21, the second thyristor bridge circuit 22 and the third thyristor bridge circuit 23. The 3 compensation transformers 40 are respectively denoted as the A-phase compensation transformer T 2a , the B-phase compensation transformer T 2b and the C-phase compensation transformer T 2c . The A-phase energy-taking transformer T 1a , the first thyristor bridge circuit 21 are respectively corresponding to the A-phase compensation transformer T 2a ; the B-phase energy-taking transformer T1b and the second thyristor bridge circuit 22 corresponds to the B-phase compensation transformer T respectively 2b correspondingly; The C-phase energy-taking transformer T 1c and the third thyristor bridge circuit 23 correspond to the C-phase compensation transformer T respectively 2c correspondingly.

[0076] As another example, as Figure 2 shown, the energy-taking transformer 30 and the thyristor bridge circuit 20 correspond to the compensation transformer 40 one by one.

[0077] Exemplarily, the compensation transformer 40 is used to achieve electrical isolation between the thyristor bridge circuit 20 and the power supply line, and is also used to magnetically couple and transfer the target compensation voltage from the thyristor bridge circuit 20 to the power supply line.

[0078] It should be noted that the value of N can be set according to the actual situation and is not limited here.

[0079] It is worth mentioning that both the energy-taking transformer 30 and the compensation transformer 40 are mainly applicable to the distribution network of 10 kV and below, and their specific capacities and compensation depths are calculated and selected according to the user's load end conditions.

[0080] For each energy-taking transformer 30, its primary side winding is adjustably connected to the power supply line of its corresponding load 50, and its secondary side tap is connected to its corresponding thyristor bridge circuit 20; among them, the number of taps of each energy-taking transformer 30 is n, and n is a positive integer.

[0081] Exemplarily, as Figure 1 shown, the power supply line of the load 50 includes an A-phase power supply line, a B-phase power supply line, and a C-phase power supply line. The primary side winding of the A-phase energy-taking transformer T 1a is adjustably connected to the A-phase power supply line of its corresponding load 50, and the secondary side taps of the A-phase energy-taking transformer T 1a are respectively connected to the first thyristor bridge circuit 21; the primary side winding of the B-phase energy-taking transformer T 1b is adjustably connected to the B-phase power supply line of its corresponding load 50, and the secondary side taps of the B-phase energy-taking transformer T 1b are respectively connected to the second thyristor bridge circuit 22; the primary side winding of the C-phase energy-taking transformer T 1c is adjustably connected to the C-phase power supply line of its corresponding load 50, and the secondary side taps of the C-phase energy-taking transformer T 1c are respectively connected to the third thyristor bridge circuit 23.

[0082] Each thyristor bridge circuit 20 is respectively connected to the primary side of its corresponding compensation transformer 40.

[0083] Exemplarily, asFigure 1 As shown, the first thyristor bridge circuit 21 is connected to the primary side of the A-phase compensation transformer T 2a ; the second thyristor bridge circuit 22 is connected to the primary side of the B-phase compensation transformer T 2b ; the third thyristor bridge circuit 23 is connected to the primary side of the C-phase compensation transformer T 2c .

[0084] Each compensation transformer 40 has its secondary side connected to its corresponding power supply line respectively.

[0085] Exemplarily, as Figure 1 shown, the secondary side of the A-phase compensation transformer T 2a is connected to its corresponding A-phase power supply line; the secondary side of the B-phase compensation transformer T 2b is connected to its corresponding B-phase power supply line; the secondary side of the C-phase compensation transformer T 2c is connected to its corresponding C-phase power supply line.

[0086] Among them, each power-taking transformer 30 obtains electric energy from the power grid connected to its corresponding power supply line, and when its corresponding thyristor bridge circuit 20 is in the target gear, converts the electric energy into a target compensation voltage, and then outputs the target compensation voltage to its corresponding power supply line through its corresponding thyristor bridge circuit 20 and its corresponding compensation transformer 40, so as to compensate the current load voltage of the load 50, and further control the voltage of the load 50 within a preset range; among them, the target compensation voltage is the compensation voltage corresponding to the target gear, and the target gear is the compensation gear corresponding to the current load voltage among n*(n - 1)+1 gears.

[0087] Exemplarily, the preset range can be considered as the allowable deviation range of the voltage of the load 50. The preset range can be set according to the actual situation and is not limited here. For example, the preset range can be [0.9V1, 1.1V1], where V1 is the rated load voltage of the load 50.

[0088] Exemplarily, the A-phase power-taking transformer T 1a obtains the first electric energy from the power grid connected to its corresponding A-phase power supply line, and when the corresponding first thyristor bridge circuit 21 of the A-phase power-taking transformer T 1a is in the target gear, converts the first electric energy into the target A-phase compensation voltage. Then, through the corresponding first thyristor bridge circuit 21 of the A-phase power-taking transformer T 1a , and the corresponding A-phase compensation voltage transformer T of the A-phase power-taking transformer T 1a , to the A-phase power-taking transformer T 2a , 1aThe corresponding phase-A power supply line outputs a target phase-A compensation voltage to compensate the current phase-A voltage of the load 50, thereby controlling the voltage of the load 50 within a preset range. The phase-B energy extraction transformer T 1b and the phase-C energy extraction transformer T 1c are implemented in a similar process as the above implementation process, which will not be elaborated here.

[0089] Since in a topological structure with the same number of compensation levels, the thyristor bridge circuit can effectively reduce the number of thyristor groups and the number of transformer taps. Therefore, according to the voltage compensator provided by the embodiments of the present application, by using a dynamic voltage restorer, a thyristor bridge circuit, and a compensation transformer to construct a voltage compensator, while ensuring that n*(n - 1)+1 levels are provided to compensate the current voltage of the load, thereby controlling the voltage of the load within a preset range, keeping the voltage of the load stable, ensuring the safe operation of the load, it can effectively reduce the number of thyristors and the number of energy extraction transformer tap positions. Compared with the dynamic voltage restorer in the prior art, the voltage compensator provided by the embodiments of the present application can effectively reduce costs.

[0090] It should be noted that, for example, in the topology Figure 2 it is shown that a compensation depth of ±30% can be output, with each 5% as a level, a total of 13 levels. Only 8 groups of bidirectional antiparallel thyristor groups and 4 transformer taps are required to achieve this. If the bridge circuit is not used, the number of output levels is the same as the number of thyristor groups and transformer taps.

[0091] In addition, for the voltage compensator provided by the embodiments of the present application, the wiring of the box body is simpler, which can effectively reduce the design cost, and the insulation design is easier to implement.

[0092] In some embodiments, as Figure 1 and Figure 2 shown, the voltage compensator further includes:

[0093] At least one protection module 10, each protection module 10 is connected in parallel with its corresponding thyristor bridge circuit 20 between the two ends of the primary side of its corresponding compensation transformer 40, and is used to prevent the secondary side tap of the energy extraction transformer 30 corresponding to the protection module 10 from being short-circuited during the switching process of its corresponding thyristor bridge circuit 20.

[0094] Exemplarily, as Figure 1 shown, the voltage compensator includes 3 protection modules 10. For the convenience of description, the 3 protection modules 10 are respectively denoted as the first protection module 11, the second protection module 12, and the third protection module 13. Among them, the first protection module 11 is connected in parallel with the first thyristor bridge circuit 21 on the primary side of the phase-A compensation transformer T 2abetween the two ends of the primary side of; the second protection module 12 and the second thyristor bridge circuit 22 are connected in parallel between the two ends of the primary side of the B-phase compensation transformer T 2b between the two ends of the primary side of; the third protection module 13 and the third thyristor bridge circuit 23 are connected in parallel between the two ends of the primary side of the C-phase compensation transformer T 2c between the two ends of the primary side of.

[0095] More specifically, during the shift switching process of the thyristor bridge circuit 20 corresponding to each protection module 10, each protection module 10 is cut off to prevent the short circuit of the secondary side tap of the energy-taking transformer 30 corresponding to the protection module 10.

[0096] In some examples, each thyristor bridge circuit 20 includes a first thyristor unit to an nth thyristor unit; the first thyristor unit includes a first thyristor group and an (n + 1)th thyristor group, the second thyristor unit includes a second thyristor group and an (n + 2)th thyristor group,..., the nth thyristor unit includes an nth thyristor group and a 2nth thyristor group;

[0097] The primary side winding of each energy-taking transformer 30 includes a first tap to an nth tap; the secondary side winding of each energy-taking transformer 30 includes an (n + 1)th tap to an mth tap; where m is a positive integer greater than n;

[0098] The first ends and second ends of each first thyristor unit to each nth thyristor unit are respectively connected in series with the two ends of the primary side of the compensation transformer 40 corresponding to them;

[0099] The third end of each ith thyristor unit is connected to its corresponding ith tap, where i is an integer greater than or equal to 1 and less than or equal to n;

[0100] Each mth tap is grounded, and one of the taps from the (n + 1)th tap to the (m - 1)th tap is adjustably connected to the power supply line of the load 50 connected to the corresponding energy-taking transformer 30.

[0101] As an example, each thyristor group in the first thyristor group to the 2nth thyristor group includes two thyristors connected in reverse parallel. Among them, the reverse parallel connection can be that the two thyristors conduct unidirectionally, and the cathode of one thyristor is connected to the anode of the other thyristor, and the anode of one thyristor is connected to the cathode of the other thyristor.

[0102] As another example, each thyristor group in the first thyristor group to the 2nth thyristor group includes at least one bidirectional thyristor.

[0103] It should be noted that the value of m can be 2n, that is, the primary side winding and the secondary side winding of each energy-taking transformer 30 have the same number of taps; the value of m can be greater than or less than 2n, that is, the number of taps of the primary side winding and the secondary side winding of each energy-taking transformer 30 is different, and no limitation is made here.

[0104] In some more specific examples, n = 4.

[0105] That is to say, as Figure 1 and Figure 2 shown, each thyristor bridge circuit 20 includes a first thyristor unit to a fourth thyristor unit; the first thyristor unit includes a first thyristor group S1 and a fifth thyristor group S5, the second thyristor unit includes a second thyristor group S2 and a sixth thyristor group S6, the third thyristor unit includes a third thyristor group S3 and a seventh thyristor group S7, the fourth thyristor unit includes a fourth thyristor group S4 and an eighth thyristor group S8; the primary side windings of each energy extraction transformer 30 include a first tap, a second tap, a third tap, and a fourth tap; the secondary side windings of each energy extraction transformer 30 include a fifth tap, a sixth tap, a seventh tap to an eighth tap; each first thyristor unit is connected to its corresponding first tap, each second thyristor unit is connected to its corresponding second tap, each third thyristor unit is connected to its corresponding third tap, each fourth thyristor unit is connected to its corresponding fourth tap; each eighth tap is grounded, and one of each fifth tap to each seventh tap is adjustably connected to the power supply line of the load connected to its corresponding energy extraction transformer 30.

[0106] Exemplarily, please refer to Figure 1 and Figure 2 , taking the first thyristor bridge circuit 21 as an example, the first thyristor unit of the first thyristor bridge circuit 21 is connected to the first tap of the A-phase energy extraction transformer T 1a ; the second thyristor unit of the first thyristor bridge circuit 21 is connected to the second tap of the A-phase energy extraction transformer T 1a ; the third thyristor unit of the first thyristor bridge circuit 21 is connected to the third tap of the A-phase energy extraction transformer T 1a ; the fourth thyristor unit of the first thyristor bridge circuit 21 is connected to the fourth tap of the A-phase energy extraction transformer T 1a ; the eighth tap of the A-phase energy extraction transformer T 1a is grounded, and one of the fifth tap and the seventh tap of the A-phase energy extraction transformer T 1a is adjustably connected to the A-phase power supply line. The connection principles of the second thyristor bridge circuit 22 and the third thyristor bridge circuit 23 are similar to those of the first thyristor bridge circuit 21 and will not be elaborated here.

[0107] In some examples, each compensation transformer 40 includes an isolation transformer.

[0108] In some examples, each protection module 10 includes a current-limiting reactor L and a thyristor group S0 connected in series between the two ends of the primary side of its corresponding compensation transformer 40.

[0109] Please refer to Figure 1 andFigure 2 , taking the first protection module 11 as an example, the first protection module may include a current-limiting resistor L and a thyristor group S0 connected in series between both ends of the primary side of the phase-A compensation transformer T 2a . The second protection module 12 and the third protection module 13 are similar to the first protection module 11, and will not be elaborated here.

[0110] Exemplarily, the thyristor group S0 includes two thyristors connected in reverse parallel.

[0111] It should be noted that whether the protection module 10 is used can be controlled by switching the thyristor group S0 on and off. The current-limiting reactor L is used to limit the excessive short-circuit current generated when the bypass where the protection module 10 is located is switched, so as to damage the thyristor group in the control gear of the corresponding thyristor bridge circuit 20.

[0112] It can be understood that, as Figure 2 shown, according to the direction of the induced short-circuit current, the waveform of an alternating current cycle is sinusoidal, and the thyristor on the left conducts in the upper half cycle, and the thyristor on the right conducts in the lower half cycle for the thyristor group S0.

[0113] It should be noted that Figure 2 the U in load represents the load voltage, the I load represents the load current, and the arrow represents the flowing direction of the load current.

[0114] Embodiment 2

[0115] The voltage compensator control method provided by the embodiment of the present application can be applied to the process of the power supply system supplying power to the load.

[0116] The voltage compensator control method provided by the embodiment of the present application can be executed by a controller in the power supply system.

[0117] The voltage compensator control method provided by the embodiment of the present application can be applied to the voltage compensator of Embodiment 1. As Figure 1 and Figure 2 shown, this method includes Step S110 to Step S120.

[0118] S110. Control each energy-taking transformer 30 to obtain electric energy from the power grid connected to its corresponding power supply line.

[0119] S120. Control the thyristor bridge circuit 20 corresponding to each energy-taking transformer 30 to be in a target gear, and the target gear is the compensation gear corresponding to the current load voltage among n*(n - 1)+1 gears.

[0120] Among them, when each energy extraction transformer 30 is in the target gear of its corresponding thyristor bridge circuit 20, the electric energy is converted into a target compensation voltage, and through the thyristor bridge circuit 20 and the compensation transformer 40 corresponding to each energy extraction transformer 30 respectively, the target compensation voltage is output to the power supply line corresponding to each energy extraction transformer 30, so as to compensate the current load voltage of the load 50, and further control the voltage of the load 50 within a preset range; wherein, the target compensation voltage is the compensation voltage corresponding to the target gear.

[0121] In a topology structure with the same number of compensation gears, the thyristor bridge circuit can effectively reduce the number of thyristor groups and the number of transformer taps. Therefore, according to the voltage compensator control method provided by the embodiments of the present application, by first controlling each energy extraction transformer 30 to obtain electric energy from the power grid connected to its corresponding power supply line, then controlling the thyristor bridge circuit 20 corresponding to each energy extraction transformer 30 to be in the target gear, and then controlling each energy extraction transformer 30 to convert the electric energy into the target compensation voltage, and through the thyristor bridge circuit 20 and the compensation transformer 40 corresponding to each energy extraction transformer 30 respectively, the target compensation voltage is output to the power supply line corresponding to each energy extraction transformer 30, so as to compensate the current load voltage of the load 50, and further control the voltage of the load 50 within a preset range, and further control the voltage of the load within a preset range, so that the voltage of the load remains stable and the safety of the load is ensured.

[0122] In addition, the thyristor bridge circuit can effectively reduce the number of thyristor groups and the number of transformer taps. Therefore, according to the embodiments of the present application, by using a dynamic voltage restorer, a thyristor bridge circuit and a compensation transformer to construct a voltage compensator, while ensuring that n*(n - 1)+1 gears are provided to compensate the current load voltage, and further controlling the voltage of the load within a preset range, so that the voltage of the load remains stable and the safety of the load is ensured, the number of thyristors and the number of tap positions of the energy extraction transformer can be effectively reduced. Compared with the dynamic voltage restorer in the prior art, the voltage compensator provided by the embodiments of the present application can effectively reduce the cost.

[0123] The specific implementation manners of the above steps will be described below.

[0124] In step S110, exemplarily, as Figure 1 and Figure 2 shown, control the phase A energy extraction transformer T 1a to obtain electric energy from the power grid connected to the phase A power supply line, and / or control the phase B energy extraction transformer T 1b to obtain electric energy from the power grid connected to the phase B power supply line, and / or control the phase C energy extraction transformer T 1c to obtain electric energy from the power grid connected to the phase C power supply line.

[0125] In some embodiments, controlling each energy-taking transformer 30 to obtain electric energy from the power grid connected to its corresponding power supply line specifically includes:

[0126] When it is monitored that the current load voltage of the load 50 is less than the preset voltage and the arm currents on each thyristor bridge circuit 20 are all completely zero-crossing, control each energy-taking transformer 30 to obtain electric energy from the power grid connected to its corresponding power supply line.

[0127] In this embodiment, when it is monitored that the current load voltage of the load 50 is less than the preset voltage and the arm currents on each thyristor bridge circuit 20 are all completely zero-crossing, controlling each energy-taking transformer 30 to obtain electric energy from the power grid connected to its corresponding power supply line can improve the safety of the voltage compensator.

[0128] Exemplarily, the A-phase power supply line to which the load 50 is connected is connected to an A-phase voltage transformer, the B-phase power supply line to which the load 50 is connected is connected to a B-phase voltage transformer, and the C-phase power supply line to which the load 50 is connected is connected to a C-phase voltage transformer. The controller is respectively connected to the A-phase voltage transformer, the B-phase voltage transformer, and the C-phase voltage transformer. The current load voltage of the load 50 may include at least one of the A-phase current load voltage, the B-phase current load voltage, and the C-phase current load voltage. The A-phase current load voltage can be monitored through the A-phase voltage transformer, the B-phase current load voltage can be monitored through the B-phase voltage transformer, and the C-phase current load voltage can be monitored through the C-phase voltage transformer.

[0129] Exemplarily, the preset voltage may include at least one of the A-phase preset voltage, the B-phase preset voltage, and the C-phase preset voltage. Monitoring that the current load voltage of the load 50 is less than the preset voltage includes: monitoring that the A-phase current load voltage of the load 50 is less than the A-phase preset voltage, and / or, monitoring that the B-phase current load voltage of the load 50 is less than the B-phase preset voltage, and / or, monitoring that the C-phase current load voltage of the load 50 is less than the C-phase preset voltage. For example, if the preset voltage may include the A-phase preset voltage, the B-phase preset voltage, and the C-phase preset voltage, then monitoring that the current load voltage of the load 50 is less than the preset voltage includes: monitoring that the A-phase current load voltage of the load 50 is less than the A-phase preset voltage, monitoring that the B-phase current load voltage of the load 50 is less than the B-phase preset voltage, and monitoring that the C-phase current load voltage of the load 50 is less than the C-phase preset voltage. Another example, if the preset voltage includes the A-phase preset voltage, then monitoring that the current load voltage of the load 50 is less than the preset voltage includes: monitoring that the A-phase current load voltage of the load 50 is less than the A-phase preset voltage.

[0130] It should be noted that the A-phase preset voltage, the B-phase preset voltage, and the C-phase preset voltage can all be set according to the actual situation and are not limited herein. And at least two of the A-phase preset voltage, the B-phase preset voltage, and the C-phase preset voltage can be equal, or they can all be unequal.

[0131] Exemplarily, as Figure 1 shown, the energy-taking transformer T of phase A 1a is connected to the current transformer of phase A, and the energy-taking transformer T of phase B 1b is connected to the current transformer of phase B, and the energy-taking transformer T of phase C 1c is connected to the current transformer of phase C. The controller is respectively connected to the current transformer of phase A, the current transformer of phase B, and the current transformer of phase C. The arm currents on each thyristor bridge circuit 20 may include at least one of the arm current of phase A, the arm current of phase B, and the arm current of phase C. The arm current of phase A CTI can be monitored through the current transformer of phase A a , the arm current of phase B CTI can be monitored through the current transformer of phase B b , and the arm current of phase C CTI can be monitored through the current transformer of phase C c .

[0132] Exemplarily, the arm currents on each thyristor bridge circuit 20 are all completely zero-crossing, and may include: the arm current of phase A on each thyristor bridge circuit 20 is completely zero-crossing, and / or, the arm current of phase B on each thyristor bridge circuit 20 is completely zero-crossing, and / or, the arm current of phase C on each thyristor bridge circuit 20 is completely zero-crossing. For example, if the arm currents on each thyristor bridge circuit 20 include the arm current of phase A CTI a , the arm current of phase B CTI b , and the arm current of phase C CTI c , then the arm currents on each thyristor bridge circuit 20 are all completely zero-crossing, including: the arm current of phase A CTI a on each thyristor bridge circuit 20 is completely zero-crossing, the arm current of phase B CTI b on each thyristor bridge circuit 20 is completely zero-crossing, and the arm current of phase C CTI c on each thyristor bridge circuit 20 is completely zero-crossing. Another example, if the arm currents on each thyristor bridge circuit 20 include the arm current of phase A CTI a , then the arm currents on each thyristor bridge circuit 20 are all completely zero-crossing, including: the arm current of phase A CTI a on each thyristor bridge circuit 20 is completely zero-crossing.

[0133] That is to say, in the embodiment of the present application, the arm currents on each thyristor bridge circuit 20 are monitored through the current transformer. During the gear shifting process, the pilot protection module 10 is first turned on, and then the zero-crossing detection is performed on the arm currents monitored by the current transformer. After completely zero-crossing, other gears (i.e., the target gear) are turned on.

[0134] In step S120, in some embodiments, before controlling the thyristor bridge circuit 20 corresponding to each energy-taking transformer 30 to be in the target gear, the method further includes:

[0135] Obtain the current load voltage and the rated load voltage corresponding to each energy-taking transformer 30 respectively, so as to obtain N current load voltages and N rated load voltages;

[0136] Determine the target gear of the thyristor bridge circuit 20 corresponding to each energy-taking transformer 30 according to the N current load voltages and the N rated load voltages.

[0137] In this embodiment, through the N current load voltages and the N rated load voltages, the target gear of the thyristor bridge circuit 20 corresponding to each energy-taking transformer 30 can be determined quickly and accurately.

[0138] Exemplarily, N = 3, and the three rated load voltages can be the rated load voltage of phase A, the rated load voltage of phase B, and the rated load voltage of phase C. The value of the rated load voltage can be set according to the actual situation and is not limited here. For example, it can be 220V or 380V, etc.

[0139] It should be noted that the N rated load voltages can be the same or different, which is not limited here.

[0140] Exemplarily, the N rated load voltages can be pre-stored in the controller for subsequent direct call. Or, relevant technical materials of the load 50 can be consulted to obtain the rated load voltage of the load.

[0141] In some examples, determining the target gear of the thyristor bridge circuit 20 corresponding to each energy-taking transformer 30 according to the N current load voltages and the N rated load voltages specifically includes:

[0142] For each energy-taking transformer 30, the following steps are respectively executed to determine the target gear of the thyristor bridge circuit 20 corresponding to each energy-taking transformer 30:

[0143] Determine the difference between the rated load voltage corresponding to the energy-taking transformer 30 and the current load voltage corresponding to the energy-taking transformer 30 as the first voltage difference;

[0144] Take the ratio of the first voltage difference to the current load voltage corresponding to the energy-taking transformer 30 as the first voltage ratio;

[0145] Determine the gear corresponding to the first voltage ratio as the target gear.

[0146] In this embodiment, according to the above method, the target gear can be further determined quickly and accurately.

[0147] Exemplarily, each gear in the n*(n - 1)+1 gears corresponds to a compensation range one by one. The compensation range where the first voltage ratio is located is determined as the target compensation range, and the gear corresponding to the target compensation range is determined as the target gear.

[0148] Exemplarily, taking the energy-taking transformer T of phase A 1a as an example, the current voltage of the load corresponding to the energy-taking transformer T of phase A 1a is a1, and the rated voltage of the load corresponding to the energy-taking transformer T of phase A 1a is a2. Then the first voltage difference is a2 - a1, and the first voltage ratio is (a2 - a1) / a1. If the first voltage ratio is within the compensation range corresponding to the first gear, the first gear is determined as the target gear. The implementation processes of the energy-taking transformer T of phase B 1b and the energy-taking transformer T of phase C 1c are the same and will not be elaborated here.

[0149] It should be noted that if a2 - a1 is a positive number, it means that the current voltage of the load is lower than the rated voltage of the load. At this time, a forward gear needs to be selected, such as the +5% gear; if a2 - a1 is a negative number, it means that the current voltage of the load is higher than the rated voltage of the load. At this time, a reverse gear needs to be selected, such as the -5% gear.

[0150] In some embodiments, each thyristor bridge circuit 20 includes a first thyristor unit to an nth thyristor unit; the first thyristor unit includes a first thyristor group and an (n + 1)th thyristor group, the second thyristor unit includes a second thyristor group and an (n + 2)th thyristor group,..., the nth thyristor unit includes an nth thyristor group and a 2nth thyristor group;

[0151] The primary side windings of each energy-taking transformer 30 include a first tap to an nth tap; the secondary side windings of each energy-taking transformer 30 include an (n + 1)th tap to an mth tap; where m is a positive integer greater than n;

[0152] The first ends and second ends of each first thyristor unit to each nth thyristor unit are respectively connected in series with both ends of the primary side of its corresponding compensation transformer 40;

[0153] Each ith thyristor unit is connected to its corresponding ith tap, where i is an integer greater than or equal to 1 and less than or equal to n;

[0154] Each mth tap is grounded, and one of the taps from the (n + 1)th tap to the (m - 1)th tap is adjustably connected to the power supply line of the load 50 connected to its corresponding energy-taking transformer 30;

[0155] The voltage compensator further includes N protection modules 10. Each protection module 10 is connected in parallel with its corresponding thyristor bridge circuit 20 between the two ends of the primary side of its corresponding compensation transformer 40, and is used to prevent the secondary side tap of the energy-taking transformer 30 corresponding to the protection module 10 from being short-circuited during the switching-on and switching-off process of its corresponding thyristor bridge circuit 20.

[0156] In the case of the target gear position of each energy-taking transformer 30, the protection modules 10 corresponding to each energy-taking transformer 30 are turned on, and the first thyristor group to the nth thyristor group are all turned off. Or, all the protection modules 10 are turned off, and one of the first thyristor group to the nth thyristor group corresponding to each energy-taking transformer 30 is turned on, and the rest are all turned off, and one of the (n + 1)th thyristor group to the 2nth thyristor group corresponding to each energy-taking transformer 30 is turned on, and the rest are all turned off.

[0157] That is to say, in this embodiment, the controller controls the protection module 10 to be turned on or off, and each thyristor group in the first thyristor group to the 2nth thyristor group to be turned on or off, so that the thyristor bridge circuit 20 corresponding to each energy-taking transformer 30 is in the target gear position.

[0158] In some examples, please refer to Figure 1 and Figure 2 , n = 4;

[0159] In the case where the target gear position is the zero gear position, the protection modules 10 corresponding to each energy-taking transformer 30 are turned on, and the first thyristor group to the eighth thyristor group corresponding to each energy-taking transformer 30 are all turned off.

[0160] In the case where the target gear position is the first gear position, the third thyristor group S3 and the eighth thyristor group S8 corresponding to each energy-taking transformer 30 are turned on, and the rest of the thyristor groups and each protection module 10 are all turned off;

[0161] In the case where the target gear position is the second gear position, the first thyristor group S1 and the sixth thyristor group S6 corresponding to each energy-taking transformer 30 are turned on, and the rest of the thyristor groups and each protection module 10 are all turned off;

[0162] In the case where the target gear position is the third gear position, the second thyristor group S2 and the seventh thyristor group S7 corresponding to each energy-taking transformer 30 are turned on, and the rest of the thyristor groups and each protection module 10 are all turned off;

[0163] In the case where the target gear position is the fourth gear position, the second thyristor group S2 and the eighth thyristor group S8 corresponding to each energy-taking transformer 30 are turned on, and the rest of the thyristor groups and each protection module 10 are all turned off;

[0164] When the target gear is the fifth gear, the first thyristor group S1 corresponding to each energy-taking transformer 30 conducts, and the seventh thyristor group S7 conducts, while the remaining thyristor groups and each protection module 10 are all cut off;

[0165] When the target gear is the sixth gear, the first thyristor group S1 corresponding to each energy-taking transformer 30 conducts, and the eighth thyristor group S8 conducts, while the remaining thyristor groups and each protection module 10 are all cut off;

[0166] When the target gear is the seventh gear, the fourth thyristor group S4 corresponding to each energy-taking transformer 30 conducts, and the seventh thyristor group S7 conducts, while the remaining thyristor groups and each protection module 10 are all cut off;

[0167] When the target gear is the eighth gear, the second thyristor group S2 corresponding to each energy-taking transformer 30 conducts, and the fifth thyristor group S5 conducts, while the remaining thyristor groups and each protection module 10 are all cut off;

[0168] When the target gear is the ninth gear, the third thyristor group S3 corresponding to each energy-taking transformer 30 conducts, and the sixth thyristor group S6 conducts, while the remaining thyristor groups and each protection module 10 are all cut off;

[0169] When the target gear is the tenth gear, the fourth thyristor group S4 corresponding to each energy-taking transformer 30 conducts, and the sixth thyristor group S6 conducts, while the remaining thyristor groups and each protection module 10 are all cut off;

[0170] When the target gear is the eleventh gear, the third thyristor group S3 corresponding to each energy-taking transformer 30 conducts, and the fifth thyristor group S5 conducts, while the remaining thyristor groups and each protection module 10 are all cut off;

[0171] When the target gear is the twelfth gear, the fourth thyristor group S4 corresponding to each energy-taking transformer 30 conducts, and the fifth thyristor group S5 conducts, while the remaining thyristor groups and each protection module 10 are all cut off.

[0172] Exemplarily, taking n = 4, the first tap of each energy-taking transformer 30 is 0, its second tap is 10% of the load rated voltage, its third tap is 25% of the load rated voltage, and its fourth tap is 30% of the rated voltage as an example, the 8 pairs of unidirectional antiparallel thyristors are controlled to be compensated in 13 bidirectional gears, with one gear set every 5%, and the compensation range is ±30%. The conducting thyristors corresponding to the corresponding gears are set as shown in Table 1 below.

[0173] Table 1

[0174]

[0175]

[0176] It should be noted that all thyristors not mentioned in Table 1 are in the cut-off state. For example, when the gear is 0, S1 - S8 are all in the cut-off state. Gear 0 is the zeroth gear, gear 5% is the first gear, gear 10% is the second gear, and so on. Gear -30% is the twelfth gear. Table 1 takes a compensation step of 5% as an example. In actual implementation, the compensation step can be other values, which are not limited here.

[0177] To better understand the voltage compensator and its control method provided by the embodiments of the present application, the following will be described in conjunction with a specific implementation manner.

[0178] The embodiments of the present application provide a thyristor-controlled transformer series-parallel dynamic voltage compensator (i.e., voltage compensator), which mainly consists of: a thyristor bridge circuit and a bypass shift transition circuit (i.e., protection module), a control system (i.e., controller), a parallel energy-taking transformer (i.e., energy-taking transformer), and a series compensation transformer (i.e., compensation transformer).

[0179] The thyristor bridge circuit is composed of multiple pairs of unidirectional antiparallel thyristors to form a bridge circuit. One end of the upper and lower bridge arms is respectively connected to both ends of the primary side of the series compensation transformer, and the other end is respectively connected to the secondary side tap and the two lead wires (i.e., the first tap to the nth tap) of the parallel energy-taking transformer. Different thyristors are turned on to achieve switching of different transformer gears.

[0180] The bypass shift transition circuit consists of a current-limiting reactor and a group of unidirectional antiparallel thyristors, which can be used as the equipment bypass. At the same time, it conducts during the shift switching process to prevent damage to the equipment caused by the short circuit of the secondary side tap of the transformer due to the simultaneous conduction of the upper and lower bridge arms of the thyristor at a certain moment during shifting.

[0181] The control system uses a digital signal processing (DSP) chip as the main controller for real-time control. The peripheral circuit mainly includes functions such as data acquisition, device communication, and device protection.

[0182] The parallel energy-taking transformer has an adjustable primary side winding, which is mainly compatible with application scenarios such as medium and low voltage power distribution. The secondary side has multiple taps and is designed according to the required number of gears.

[0183] The series compensation transformer uses an isolation transformer. The primary side is connected to the thyristor group, and the secondary side is connected in series to the main power supply line (i.e., power supply line).

[0184] The dynamic voltage compensator based on thyristor control provided by the embodiments of the present application mainly consists of an energy-taking transformer with 4 taps, a series-connected transformer (i.e., a compensation transformer), a thyristor switching unit (i.e., a thyristor bridge circuit) using 8 pairs of unidirectional antiparallel thyristors, a bypass current-limiting reactor (i.e., a current-limiting reactor), and a control system (i.e., a controller). When the monitored voltage on the load side is too low, the multi-tap energy-taking transformer will draw energy from the power grid, and through thyristor control, the transformer tap output will compensate the load voltage to a compensation voltage near the required amplitude of the rated voltage, which is superimposed on the system power supply through the series transformer on the line, so that the voltage on the load side remains stable and ensures the safe operation of the load side.

[0185] The switching control (i.e., the voltage compensator control method) of the series-parallel dynamic voltage compensator based on thyristor control transformer in the embodiments of the present application is as follows: The voltage transformer is used to detect the load voltage value and the current transformer monitors the thyristor bridge arm current, and the monitored values are sent to the control system. When the load voltage (i.e., the current load voltage) is within the rated range, at this time, the bypass thyristor (i.e., the thyristor) of the device controls the start of the device bypass (i.e., the protection module), and the thyristor gear control signal is locked. When the detected load side voltage (i.e., the current load voltage) rises or falls beyond the rated range, the control system (i.e., the controller) will automatically select an appropriate switching gear through the difference between the current load voltage value and the set rated value (i.e., the load rated voltage). After turning on the control thyristor of the corresponding gear, the bypass thyristor is disconnected.

[0186] As Figure 1 shown, the circuit is a single-phase compensation gear topology example diagram. 10%, 25%, and 30% are respectively taken out from the secondary side taps of the parallel energy-taking transformer, and are controlled by 8 pairs of unidirectional antiparallel thyristors and divided into 13 bidirectional gears for compensation. One gear is set every 5%, and the compensation range is ±30%. The conduction thyristors corresponding to the corresponding gears are set as shown in Table 1 above.

[0187] Taking Figure 1 the circuit topology for single-phase voltage compensation system simulation. The system voltage Us is 3300V, the simulated line impedance voltage drop is about 300V, the device (i.e., the voltage compensator) is put into operation for boost compensation operation, and the control strategy is 0-gear control at the initial time and 30%-gear control at 0.02s (S1 and S8 thyristors are turned on). The voltage on the load side rises. The thyristor group trigger signals are as Figure 3 、 Figure 4 、 Figure 5 shown. It can be clearly seen that the load voltage UI is lower than the system voltage and drops before 0.2s, and the device is put into use after 0.2s. The diagram of the voltage change at both ends of the load with the switching of the device is as Figure 6 shown. As Figure 6It can be seen that the series-parallel dynamic voltage compensator based on a thyristor-controlled transformer provided by the embodiments of the present application can effectively compensate the load-side voltage, with good control process accuracy, a small voltage difference between switching gears, and effectively reduce the impact on the main circuit. Among them, Figures 3 to 6 In it, the abscissa represents time t, with the unit of s (second); the ordinate is voltage, with the unit of V (volt); Figure 6 In it, U s represents the system voltage, and U l represents the load voltage.

[0188] The embodiments of the present application provide a series-parallel dynamic voltage compensator based on a thyristor-controlled transformer for power quality governance. It mainly includes a thyristor group, a control system, a parallel energy-taking transformer, and a series compensation transformer. Among them, the thyristor group is composed of a bridge-type thyristor gear control circuit and a bypass shift transition circuit. The primary side winding of the parallel energy-taking transformer is adjustable and is connected in parallel to the load-side power supply line, and the secondary side taps and the two ends of the leads are respectively connected to the bridge-type thyristor group. The primary side of the series compensation transformer is connected to the two arms of the thyristor group, and the secondary side is connected in series to the power supply line. The embodiments of the present application are used to monitor the load-side voltage and obtain electrical energy, and then output different magnitudes of voltage to the main power supply line through the series compensation transformer. It can effectively solve the problem of voltage fluctuations in the distribution network, realize the autonomous regulation of the distribution network voltage, and effectively improve the power quality.

[0189] The embodiments of the present application at least have the following beneficial effects:

[0190] 1. Using a thyristor bridge circuit to achieve two-way compensation ability, and at the same time, the maximum number of control gear positions can be obtained by combining the switching of the minimum number of thyristor groups and transformer taps. The wiring of the box body is more convenient, effectively reducing the design cost, and the insulation design is easier to achieve.

[0191] 2. A two-way thyristor and a current-limiting reactor are connected in parallel at both ends of the primary side of the series compensation transformer, effectively avoiding the problem of short circuit of the secondary side taps of the parallel energy-taking transformer that may occur during the gear shifting process.

[0192] 3. The primary side winding of the parallel energy-taking transformer can be adjusted through different taps, which is compatible with medium and low voltage occasions and improves the voltage application range of the device.

[0193] Embodiment 3

[0194] The power supply system provided by the embodiments of the present application is applicable to the process of the power supply system supplying power to the load.

[0195] As Figure 1 and Figure 2 shown, the power supply system provided by the embodiments of the present application may include:

[0196] Load 50;

[0197] A power supply line, connected to a load 50, for supplying power to the load 50;

[0198] A voltage compensator as in any one of Embodiment 1, connected to the power supply line, for compensating the current load voltage of the load 50 to control the voltage of the load 50 within a preset range.

[0199] In some embodiments, the system further includes:

[0200] A controller, connected to the voltage compensator, for controlling the voltage compensator to compensate the current load voltage of the load 50 to control the voltage of the load 50 within a preset range.

[0201] Exemplarily, the controller uses a digital signal processing (DSP) chip for real-time control, and the peripheral circuit mainly includes functions such as data acquisition, device communication, and device protection.

[0202] It should be noted that the controller provided in the embodiments of the present application can execute the voltage compensator control method in Embodiment 2, that is, it has the beneficial effects and implementation manners of the voltage compensator control method provided in the embodiments of the present application. Specifically, reference can be made to the specific description of the power supply system in the above Embodiment 1, and details are not described herein again in this embodiment.

[0203] The power supply system provided in the embodiments of the present application includes the voltage compensator of Embodiment 1 of the present application, that is, it has the beneficial effects and implementation manners of the voltage compensator provided in the embodiments of the present application. Specifically, reference can be made to the specific description of the power supply system in the above Embodiment 1, and details are not described herein again in this embodiment.

[0204] It can be understood that the above embodiments are merely exemplary embodiments adopted to illustrate the principle of the present application. However, the present application is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the present application, and these modifications and improvements are also regarded as the protection scope of the present application.

Claims

1. A voltage compensator, characterized in that: It comprises N energy extraction transformers (30), N thyristor bridge circuits (20) and N compensation transformers (40), wherein the energy extraction transformers (30) and the thyristor bridge circuits (20) correspond to the compensation transformers (40) one by one, respectively, and N is a positive integer; The primary winding of each energy extraction transformer (30) is adjustably connected to the power supply line of the corresponding load (50), and the secondary gear tap is connected to the corresponding thyristor bridge circuit (20); wherein the number of taps of each energy extraction transformer (30) is n, and n is a positive integer; Each of the thyristor bridge circuits (20) is connected to the primary side of its corresponding compensation transformer (40); The secondary side of each of the compensating transformers (40) is respectively connected to the corresponding power supply line; Each of the energy extraction transformers (30) obtains electric energy from a power grid to which its corresponding power supply line is connected, and when its corresponding thyristor bridge circuit (20) is in a target gear position, converts the electric energy into a target compensation voltage, and then outputs the target compensation voltage to its corresponding power supply line through its corresponding thyristor bridge circuit (20) and its corresponding compensation transformer (40), so as to compensate for the current load voltage of the load (50), thereby controlling the voltage of the load (50) within a preset range; wherein the target compensation voltage is the compensation voltage corresponding to the target gear position, and the target gear position is the compensation gear position corresponding to the current load voltage among the n*(n-1)+1 gear positions.

2. The voltage compensator according to claim 1, characterized in that: Each of the thyristor bridge circuits (20) comprises a first thyristor unit to an nth thyristor unit; the first thyristor unit comprises a first thyristor group and an n+1th thyristor group, the second thyristor unit comprises a second thyristor group and an n+2th thyristor group, ..., the nth thyristor unit comprises an nth thyristor group and a 2nth thyristor group; The primary winding of each energy extraction transformer (30) includes a first tap to an nth tap; the secondary winding of each energy extraction transformer (30) includes an n+1th tap to an mth tap; wherein m is a positive integer greater than n; The first end and the second end of each of the first thyristor units to each of the nth thyristor units are respectively connected in series to two ends of the primary side of a compensation transformer (40) corresponding thereto; The third end of each i-th thyristor unit is connected to its corresponding i-th tap, where i is an integer greater than or equal to 1 and less than or equal to n; Each of the m-th taps is grounded, and one of the n+1-th taps to the m-1-th tap is adjustable to be connected to a power supply line of a load (50) connected to the corresponding energy extraction transformer (30).

3. The voltage compensator according to claim 2, characterized in that: n＝4。 4. The voltage compensator according to any one of claims 1 to 3, characterized in that: The voltage compensator further comprises: At least one protection module (10), each protection module (10) and its corresponding thyristor bridge circuit (20) are connected in parallel between the two ends of the primary side of its corresponding compensation transformer (40), and are used to prevent the secondary side gear tap of the energy extraction transformer (30) corresponding to the protection module (10) from short-circuiting during the gear switching process of the corresponding thyristor bridge circuit (20).

5. The voltage compensator according to claim 4, characterized in that: Each of the protection modules (10) comprises a current-limiting reactor (L) and a thyristor group (S0) connected in series between two ends of the primary side of the corresponding compensation transformer (40).

6. The voltage compensator according to claim 1, characterized in that: Each of the compensating transformers (40) comprises an isolation transformer.

7. A voltage compensator control method, characterized in that: Applied to the voltage compensator according to any one of claims 1 to 6, the method comprises: Controlling each energy-taking transformer (30) to obtain electric energy from a power grid connected to a corresponding power supply line; Controlling the thyristor bridge circuit (20) corresponding to each of the energy extraction transformers (30) to be in a target gear position, wherein the target gear position is a compensation gear position corresponding to the current voltage of the load among n*(n-1)+1 gear positions; Wherein, when the corresponding thyristor bridge circuit (20) of each energy taking transformer (30) is in a target gear position, the electric energy is converted into a target compensation voltage, and the target compensation voltage is output to the power supply line corresponding to each energy taking transformer (30) through the thyristor bridge circuit (20) and the compensation transformer (40) respectively corresponding to each energy taking transformer (30), so as to compensate for the current load voltage of the load (50), thereby controlling the voltage of the load (50) within a preset range; the target compensation voltage is the compensation voltage corresponding to the target gear position.

8. The method according to claim 7, characterized in that Before the thyristor bridge circuit (20) corresponding to each of the energy extraction transformers (30) is controlled to be in a target gear position, the method further comprises: Obtaining the load current voltage and the load rated voltage respectively corresponding to each of the energy extraction transformers (30) to obtain N load current voltages and N load rated voltages; According to the N current voltages of the loads and the N rated voltages of the loads, the target gear position of the thyristor bridge circuit (20) corresponding to each of the energy extraction transformers (30) is determined.

9. The method according to claim 8, characterized in that Determining the target gear position of the thyristor bridge circuit (20) corresponding to each of the energy taking transformers (30) according to the N current load voltages and the N rated load voltages specifically includes: For each of the energy extraction transformers (30), the following steps are respectively performed to determine the target gear position of the thyristor bridge circuit (20) corresponding to each of the energy extraction transformers (30): Determining the difference between the load rated voltage corresponding to the energy extraction transformer (30) and the load current voltage corresponding to the energy extraction transformer (30) as a first voltage difference; Taking the ratio of the first voltage difference to the current voltage of the load corresponding to the energy extraction transformer (30) as the first voltage ratio; The gear position corresponding to the first voltage ratio is determined as the target gear position.

10. The method according to claim 7, characterized in that The controlling each of the energy taking transformers (30) to obtain electric energy from a power grid connected to a corresponding power supply line specifically comprises: When it is monitored that the current load voltage of the load (50) is less than the preset voltage and the bridge arm currents on each of the thyristor bridge circuits (20) are completely zero-crossed, each of the energy extraction transformers (30) is controlled to obtain electric energy from the power grid connected to the corresponding power supply line.

11. The method according to claim 7, characterized in that Each of the thyristor bridge circuits (20) comprises a first thyristor unit to an nth thyristor unit; the first thyristor unit comprises a first thyristor group and an n+1th thyristor group, the second thyristor unit comprises a second thyristor group and an n+2th thyristor group, ..., the nth thyristor unit comprises an nth thyristor group and a 2nth thyristor group; The primary winding of each energy extraction transformer (30) includes a first tap and an nth tap; the secondary winding of each energy extraction transformer (30) includes an n+1th tap to an mth tap; wherein m is a positive integer greater than n; The first end and the second end of each of the first thyristor units to each of the nth thyristor units are respectively connected in series to two ends of the primary side of a compensation transformer (40) corresponding thereto; Each i-th thyristor unit is connected to its corresponding i-th tap, where i is an integer greater than or equal to 1 and less than or equal to n; Each of the m-th taps is grounded, and one of the n+1-th taps to the m-1-th tap is adjustable to be connected to a power supply line of a load (50) connected to the corresponding energy extraction transformer (30); The voltage compensator further comprises N protection modules (10), each of the protection modules (10) and its corresponding thyristor bridge circuit (20) being connected in parallel between the two ends of the primary side of its corresponding compensation transformer (40), and being used to prevent the secondary side gear tap of the energy extraction transformer (30) corresponding to the protection module (10) from being short-circuited during the gear switching process of the corresponding thyristor bridge circuit (20); When each of the energy taking transformers (30) corresponds to a target gear position, the protection modules (10) corresponding to each of the energy taking transformers (30) are turned on, and the first thyristor group to the nth thyristor group are all turned off, or, the protection modules (10) are all turned off, one of the first thyristor group to the nth thyristor group corresponding to each of the energy taking transformers (30) is turned on, and the other items are turned off, and one of the n+1th thyristor group to the 2nth thyristor group corresponding to each of the energy taking transformers (30) is turned on, and the other items are turned off.

12. The method according to claim 11, characterized in that n＝4； When the target gear position is the zeroth gear position, the protection modules (10) corresponding to each of the energy extraction transformers (30) are turned on, and the first to eighth thyristor groups corresponding to each of the energy extraction transformers (30) are turned off. When the target gear is the first gear, the third thyristor group (S3) and the eighth thyristor group (S8) corresponding to each of the energy extraction transformers (30) are turned on, and the remaining thyristor groups and each of the protection modules (10) are turned off; When the target gear is the second gear, the first thyristor group (S1) and the sixth thyristor group (S6) corresponding to each of the energy extraction transformers (30) are turned on, and the remaining thyristor groups and each of the protection modules (10) are turned off; When the target gear is the third gear, the second thyristor group (S2) and the seventh thyristor group (S7) corresponding to each of the energy extraction transformers (30) are turned on, and the remaining thyristor groups and each of the protection modules (10) are turned off; When the target gear is the fourth gear, the second thyristor group (S2) and the eighth thyristor group (S8) corresponding to each of the energy extraction transformers (30) are turned on, and the remaining thyristor groups and each of the protection modules (10) are turned off; When the target gear is the fifth gear, the first thyristor group (S1) and the seventh thyristor group (S7) corresponding to each of the energy extraction transformers (30) are turned on, and the remaining thyristor groups and each of the protection modules (10) are turned off; When the target gear is the sixth gear, the first thyristor group (S1) and the eighth thyristor group (S8) corresponding to each of the energy extraction transformers (30) are turned on, and the remaining thyristor groups and each of the protection modules (10) are turned off; When the target gear is the seventh gear, the fourth thyristor group (S4) and the seventh thyristor group (S7) corresponding to each of the energy extraction transformers (30) are turned on, and the remaining thyristor groups and each of the protection modules (10) are turned off; When the target gear is the eighth gear, the second thyristor group (S2) and the fifth thyristor group (S5) corresponding to each of the energy extraction transformers (30) are turned on, and the remaining thyristor groups and each of the protection modules (10) are turned off; When the target gear is the ninth gear, the third thyristor group (S3) and the sixth thyristor group (S6) corresponding to each of the energy extraction transformers (30) are turned on, and the remaining thyristor groups and each of the protection modules (10) are turned off; When the target gear is the tenth gear, the fourth thyristor group (S4) and the sixth thyristor group (S6) corresponding to each of the energy extraction transformers (30) are turned on, and the remaining thyristor groups and each of the protection modules (10) are turned off; When the target gear is the eleventh gear, the third thyristor group (S3) and the fifth thyristor group (S5) corresponding to each of the energy extraction transformers (30) are turned on, and the remaining thyristor groups and each of the protection modules (10) are turned off; When the target gear is the twelfth gear, the fourth thyristor group (S4) and the fifth thyristor group (S5) corresponding to each of the energy extraction transformers (30) are turned on, and the remaining thyristor groups and each of the protection modules (10) are turned off.

13. A power supply system, characterized in that: include: load(50); a power supply circuit, connected to the load (50) and used to supply power to the load (50); The voltage compensator according to any one of claims 1 to 6 is connected to the power supply line and is used to compensate for the current load voltage of the load (50) so as to control the voltage of the load (50) within a preset range.

14. The power supply system according to claim 13, characterized in that: The system further comprises: A controller is connected to the voltage compensator and is used to control the voltage compensator to compensate for the current load voltage of the load (50) so as to control the voltage of the load (50) to be within a preset range.

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